18/8 Stainless Steel: How It Is Made, Uses, and Properties
Learn why it’s so popular in manufacturing
Stainless steel ticks all the boxes for manufacturers looking for a durable material that can be shaped and molded into all sorts of products—and it’s is pretty to look at, too. The problem is that there are so many different types that you have to know what each one brings to the table before you can settle on which to use for 3D printing, sheet metal fabrication, or any other process. We’ll take a better look at one of the most popular stainless steels, 18/8, and share the types of applications it’s best for, as well as the ways in which Xometry can help with stainless steel processing and manufacturing for your business.
What is 18/8 Stainless Steel?
18/8 stainless steel (categorized as grade 304) contains several ingredients that funnel it into this specific category—most notably, it has around 18% chromium and 8% nickel. Although the largest alloy percentage comes from iron, these two metals give this grade its name and influence specific properties, like corrosion resistance.
Chromium is known for its oxygen barrier-forming ability, which means this type of stainless steel has a better defense against stains and corrosion. As for the nickel, this, too, wards off corrosion, but it will also give the steel extra strength and a lustrous finish to boot. Traces of other alloys can be found in 18/8, like molybdenum, silicon, nitrogen, copper, and/or titanium. To compare it to other stainless steel, 18/8 is basically the lovechild of 18/10 and 18/0.
What Is the Other Term for 18/8 Stainless Steel?
18/8 stainless steel is also known as Type 304 stainless steel. Multiple nomenclatures are used for stainless steels, with some issues in correlation between them.
The naming system for stainless steels can be complex and is primarily based on a combination of factors including: chemical composition, microstructure, and various standards set by organizations such as the American Iron and Steel Institute (AISI) and the International Organization for Standardization (ISO). Stainless steel grades are typically designated by numbers or alphanumeric codes. These grades relate to the alloy-element composition and properties of the steel. Stainless steels are primarily alloyed with chromium, nickel, molybdenum, titanium, silicon, nitrogen, and copper. Percentages of these elements denote the chemical composition of a stainless steel grade and these are used for designation of type.
How Is 18/8 Stainless Steel Made?
The process for making 18/8 stainless steel is similar to other types and involves smelting its multitude of ingredients in an electric arc furnace. Once the chromium, nickel, iron, and other alloys are added in, the metals will liquefy and then go through refining to ensure there are no impurities or unwanted chemicals, which will be separated out as slag. Then the finalized steel will harden within molds—whether you’ve chosen ingots, billets, slabs, or another shape. It will then be processed and finished and fulfill its life’s purpose of being an aerospace or automotive part or a household product (those are just examples; the world is its oyster really).
How Does 18/8 Stainless Steel Differ From 18/10 Stainless Steel?
18/8 stainless steel and 18/10 stainless steel are both austenitic stainless steels, appreciated for their excellent corrosion resistance and versatility. Both 18/8 and 18/10 stainless steels contain 18% chromium, which delivers the primary corrosion resistance through the formation of a passive oxide layer on the surface. The key difference between 18/8 and 18/10 stainless steels lies in their nickel content. 18/8 stainless steel contains 8% nickel, while 18/10 stainless steel contains 10% nickel. The higher nickel content in 18/10 stainless steel provides enhanced corrosion and reduced staining/pitting in certain environments compared to 18/8 stainless steel. The higher nickel content can contribute to a slightly brighter and more lustrous appearance. Both 18/8 and 18/10 stainless steels are commonly used in kitchenware, cutlery, appliances, and other applications in which corrosion resistance and aesthetics are important. However, 18/10 stainless steel may be preferred in more demanding environments or applications in which a higher level of corrosion resistance justifies the higher material cost.
What Grade Is 18/8 Stainless Steel?
The 18/8 designation corresponds to AISI (American Iron and Steel Institute) grade 304, which is one of the most common and widely used/referenced stainless steel grades.
What Are the Uses of 18/8 Stainless Steel?
We can’t really rave about 18/8 stainless steel enough. It’s useful in so many industries and can be made into a plethora of products, including:
- Cookware (pots, pans, cooking utensils)
- Kitchen appliances
- Architectural elements (window frames, decorative parts)
- Automotive parts (grilles, exhaust pipes, pipe systems, trim, body panels)
- Medical and dental equipment (did we mention it has hygienic properties and is easy to sterilize? It’s also biocompatible)
- Construction materials (roofing, cladding, handrails)
- Food and chemical (tanks, cans, pipes)
What Industries Utilize 18/8 Stainless Steel?
Most industries employ 18/8 stainless steel (AISI 304) due to its excellent corrosion resistance, durability, formability, and application versatility. Some examples are listed below:
- Food, Brewing, and Beverage: Use 18/8 stainless steel for equipment such as: tanks, piping, processing machinery, storage containers, and tools. Its corrosion resistance and hygienic properties make it ideal for applications in which food contact is involved.
- Automotive: Used for various components such as: exhaust systems, trim elements, grilles, fasteners, and decorative parts.
- Construction: Used for architectural elements like: handrails, door and window frames, façades, cladding, roofing, grilles, and decorative features.
- Medical and Pharmaceutical: Extensively used for manufacturing equipment, instruments, and sundry devices due to its biocompatibility, corrosion resistance, and ease of sterilization.
Why Use 18/8 Stainless Steel?
18/8 stainless steel is widely chosen for a huge range of applications for its balance of resistance to corrosion, heat, chemical damage, aesthetic appeal, and cost. It is often the preferred material due to its ease of fabrication, hygienic properties, and low maintenance requirements, contributing to its popularity across industries.
Is 18/8 Stainless Steel Suitable for Cookware?
Yes, 18/8 or 304 stainless steel is widely used for cookware and kitchen equipment due to its combination of toughness, moderate ductility in forming, and good resistance to both heat and corrosion in use and cleaning.
Can 18/8 Stainless Steel Be Used for CNC Machining?
Yes, 18/8 stainless steel is very commonly used for CNC machining components for many sectors and industries. Its excellent machinability characteristics suit it for various machining processes, including CNC processing.
18/8 stainless steel can be precisely machined to produce intricate components with tight tolerances. It exhibits good chip formation and chip evacuation properties, reducing the risk of tool wear and ensuring smooth machining operations. It maintains its mechanical properties and corrosion resistance after machining. However, appropriate machining parameters and cutting tools should be selected to optimize the machining process and minimize tool wear.
What Are the Properties of 18/8 Stainless Steel?
Table 1 below shows a selection of important properties for 18/8 or 304 stainless steel:
| Property | Value |
|---|---|
Property Density | Value 8.0 g/cm³ |
Property Melting Point | Value 1,400–1,450 °C |
Property Thermal Conductivity | Value 16.2 W/m·K at 100 °C |
Property Electrical Resistivity | Value 720 nΩ·m at 20 °C |
Property Modulus of Elasticity | Value 193 GPa |
Property Poisson's Ratio | Value 0.29 |
Property Tensile Strength | Value 515 MPa |
Property Yield Strength | Value 205 MPa |
Property Hardness (Rockwell B) | Value 70–85 HRB |
Property Hardness (Brinell) | Value 201–262 HB |
Property Corrosion Resistance | Value Excellent |
Property Magnetic Properties | Value Non-magnetic |
Properties of 18/8 Stainless Steel
These values are greatly affected by processing conditions and relatively small changes in alloying elements, so some variation between manufacturers and cold and hot rolling can be expected.
Are 18/8 Stainless Steel Weldable?
Yes, 18/8 stainless steel is generally considered weldable using common welding techniques such as: TIG (tungsten inert gas), MIG (metal inert gas), arc (stick) welding, as well as laser welding methods. However, there are some considerations to keep in mind. Preheating the material before welding and applying post-weld heat treatment may be necessary to prevent cracking and ensure proper weld integrity. Matching or slightly overmatching filler materials with a similar composition to the base metal (304 stainless steel) is recommended. Proper selection of welding parameters such as: heat input, travel speed, and shielding gas composition is crucial to achieving sound welds. To prevent contamination and maintain corrosion resistance, it's essential to use clean equipment, filler materials, and appropriate welding techniques.
Are 18/8 Stainless Steel Good Quality?
Yes, 18/8 stainless steel is generally perceived as a good-quality material. However, much depends on the nature of the application, so its suitability for aggressive chemical environments, extreme heat, marine applications, and high-stress/fatigue uses may render it unsuitable.
Does 18/8 Stainless Steel Have a High Rust Resistance?
In non-aggressive environments and with low exposure to high concentrations of chloride ions, 18/8 stainless steel is highly resistant to corrosion.
It is vulnerable to pitting corrosion when exposed to salt and some other chemistries, which can lead to brown spots, point-corrosion-forming pits, and the staining of surrounding materials with brown iron-oxide residues. Examples of this are pinhole failures in marine fuel tanks when exposed to saltwater, and brown point staining of the uncoated 304 or 18/8 sheet stainless steel used in Tesla vehicles (according to various internet-based discussions).
How Much Does 18/8 Stainless Steel Cost?
Typical prices for 18/8 stainless steel vary somewhat with process conditions. Cold-rolled coil sheets of a range of thicknesses are priced between $950 and $1,200 per tonne depending on the volume of bulk order. Small sheet purchases can be considerably more expensive, with 20 gauge ranging up to $100 per sheet (size variable). Rolled and welded tube prices vary between $1,100 and $4,300 per tonne.
Are 18/8 Stainless Steel Expensive?
Yes. 18/8 is among the more expensive grades of basic stainless steel, as it has a relatively high nickel and chromium content. Other grades such as the 400 series have either low- or zero-nickel content, making them lower cost. They also have quite different properties and are not necessarily interchangeable in most applications.
What Are the Advantages of 18/8 Stainless Steel?
There are several benefits, as well as a few downsides, you should know about when working with 18/8 stainless steel specifically. Some of its best advantages include:
- Only 18/10 has better corrosion resistance
- It’s strong and durable enough for heavy loads and mechanical stresses
- It’s hygienic stainless steel that’s easy to clean and sterilize, making it ideal food, medical, or dental workplaces
- Its bright and silvery finish is much more aesthetically pleasing than other stainless steels out there
- It’s reliable for welding, machining, or forming into complex parts
- It’s recyclable so you can do your part for the environment
What Are the Disadvantages of 18/8 Stainless Steel?
Here are the not-so-great aspects of 18/8 stainless steel:
- It’s a little more expensive than other stainless steels (you can thank the higher nickel content for that)
- It’s an austenitic stainless steel but could develop a slight magnetic pull after some cold working processes
- While it has excellent corrosion resistance, its kryptonite is saltwater, chlorinated, and highly corrosive environments, which can degrade it much quicker.
- This stainless steel has a high melting point, but at certain high temperatures, it will lose its integrity.
What Are the Differences Between 18/8, 316, and 304 Stainless Steel?
18/8, 316, and 304 stainless steel are commonly used grades of stainless steel, but they differ in terms of composition, properties, and applications.
18/8 stainless steel contains 18% chromium and 8% nickel, with small amounts of manganese and silicon. 316 stainless steel contains 16–18% chromium, 10–14% nickel, 2–3% molybdenum, and small amounts of manganese and silicon. 304 stainless steel is closely related to 18/8 stainless steel, containing 18% chromium and 8% nickel, but commonly with slightly different trace-element compositions.
18/8 stainless steel offers good corrosion resistance in most environments but may be susceptible to pitting, stress corrosion cracking, and staining in chloride-rich environments. 316 stainless steel has superior corrosion resistance, particularly in chloride-rich environments such as coastal areas and marine applications, due to the addition of molybdenum. 304 stainless steel offers good general corrosion resistance, similar to 18/8 but cannot match 316 stainless steel, particularly in chloride-rich environments.
18/8 stainless steel offers good strength and toughness, suitable for a wide range of applications. 316 stainless steel generally has higher tensile and yield strength than 304. 304 stainless steel is essentially identical in strength to 18/8 stainless steel but may have slightly divergent mechanical properties.
In application terms, 18/8 and AISI 304 are used whenever corrosion resistance is required but environments offer lower chloride-ion exposure. 316 offers additional resistance to chlorides and acids.
What Are the Differences Between 18/8, 18/10, and 18/0 Stainless Steel?
The differences between 18/8, 18/10, and 18/0 stainless steel primarily lie in their nickel content, which affects their corrosion resistance and other properties:
18/8 stainless steel contains approximately 18% chromium and 8% nickel. It offers good corrosion resistance and durability. It is suitable for a wide range of applications including: kitchenware, cookware, appliances, and architectural structures.
18/10 stainless steel contains approximately 18% chromium and 10% nickel. Its higher nickel content provides generally enhanced properties and higher luster in polished finishes. It offers enhanced corrosion resistance, particularly in aggressive environments. It is often preferred for applications requiring superior resistance to corrosion and staining, such as high-end kitchenware and cutlery.
18/0 stainless steel contains approximately 18% chromium and no nickel. It offers good corrosion resistance in mild environments, but lower than 18/8 and 18/10 stainless steel. It is generally less expensive than 18/8 and 18/10 stainless steel due to the absence of nickel. It is suitable for applications in which corrosion resistance is less critical, such as: utensils, flatware, and certain architectural elements that will get no salt exposure or are distant from view.
The choice between these materials depends on the specific requirements of the application, including: environmental conditions, aesthetics, and budget considerations.
How Xometry Can Help
Stainless steel is not only popular within the industry but also one of our most asked-about materials. We offer many different services for processing and manufacturing stainless steel, including 3D printing, injection molding, metal stamping, laser cutting, and even custom metal extrusion options.
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